The major accomplishments of this grant have been: (1) purification of a human glycoprotein hormone stimulating red cell precursors referred to as EPA; (2) molecular cloning and expression of the cDNA for EPA; (3) isolation and mapping of the human gene for EPA; (4) determination of the effects of human growth hormone and insulin on hematopoietic cells in vitro; (5) establishment of assay systems for determining growth hormone and insulin resistance in vitro; (6) establishment of a radioimmunoassay for EPA; (7) establishment of a binding assay for EPA; and (8) establishment of methods for determining the genetic or epigenetic basis of polypeptide hormone resistance. (C)